Process of making bituminous emulsions



Patented July 20, 1937 PATENT @FFEQE.

PRGCESS OF MAKING BITUMINOUS EMULSION S William F. Fair, J12, New York,N. Y., assignor to The Barrett Company, New York, N. Y., a corporationof New Jersey "No Drawing. "Application February 9, 1934,

Serial No. 710,533

2 Claims.

"This invention relates to emulsions or dispersions of bituminousmaterials, and more particularly, to coal tar emulsions and methods forproducing the same.

Heretofore, emulsions of asphalts have been made and used for surfacingroads, curing concrete, protecting iron Work, etc. In some instances,light tars have also been emulsified. Heavy coal tars,'that is coal tarshaving a specific gravity of from 1.18, or even as low as 1.15, to

1.25 or high-er at C. have not been successfully used in producingemulsions prior to the invention of my copending application Serial No.628,113, filed August 9, 1932, for the reason that emulsions of suchtars when produced by processes such as are used in producing asphalticemulsions are relatively unstable so that the tar soon settles out ofsuspension.

Coal tars generally are of higher specific gravity than asphalts andthis property may account, in part at least, for the comparativeinstability of emulsions or dispersions of coal tars as heretoforeproduced. Among the factors which influence the stability of emulsionsand tend to cause settling out of the material dispersed are differencesin density of the disperse phase and the continuous phase anddifferences in viscosity of the two phases or a combination of thesefactors With others. It has been proposed to increase the stability ofemulsions or dispersions of bituminous materials by (l) increasing thedensity of the aqueous phase and (2) by decreasing thedensity of thedisperse phase. Method (1) has been practiced heretofore by I addingclay or the like to the aqueous phase prior to the dispersion of thebituminous material. However, the resulting dispersion then containsundesired inert inorganic material. Method (2) has been used by cuttingback the bituminous material with a sumcient amount of a light organicsolvent to reduce the density and viscosity of the material dispersed.This method, it will be noted, requires the use of substantial amountsof relatively expensive solvents and changes the physical properties ofthe bituminous phase.

Among the objects of this invention are to produce bituminous emulsionsof improved sta- 'bility, and particularly, coal tar emulsions ordispersions or" improved stability; to provide an inexpensive and simplemethod by which such emulsions or dispersions can be made and to producesuch emulsions without incorporating objectionable inert inorganicmaterials therein. These and other objects of this invention will appearfrom the following description thereof.

In my copending application, hereinabove referred to, there is discloseda procedure of making coal tar emulsions involving the formation of aninitial emulsion by dispersing a relatively small amount of a suitableeasily-emulsifiable 5 bituminous material, such as asphalt, in anaqueous medium and then adding to this initial emulsion relatively heavycoal tar or Water gas tar. Asphalts, asphalt flux oil. petroleum, fueloil, or other asphaltic or petroleum bitumens may 10 be employed as thebituminous material for the disperse phase of the initial emulsion.Preferably, asphalt having a penetration at 77 F. of from 100 to 220tenths of a millimeter (determined by A. S. T. M. Standard Method D5-25)is 15 utilized. A relatively heavy coal tar having a specific gravity ofnot less than 1.15 at 25 C. and a viscosity of not less thanapproximately 60 seconds for 100 c. c. at 100 C. or a relatively heavyWater gas tar having a viscosity of not less than approximately 60seconds per 100 c. c. at '100" C. is dispersed in the initial emulsion.Heavier and more viscous coal tars, including coke oven, vertical andhorizontal retort tars, Water gas tar, or other relatively heavybituminous material of different characteristics from that forming thedisperse phase of the initial emulsion may be added to. the initialemulsion.

In producing such emulsions, preferably a soap or saponaceous materialis employed as a dispersing agent to aid in the production of both theinitial and the final emulsion. The soapforming materials may be addedto the aqueous medium and to the bituminous material to be dispersed sothat a reaction between the soapforming materials which results in theformation of soap takes place during the emulsification of thebituminous material. Preferably, the basic constituent of the soap isadded to the aqueous medium in which it is readily soluble and theacidic constituent is added to the material to be dispersed, although,if desired, the soap emulsifier, as such, or soap-forming constituentsmay be added to the emulsion during its formation or immediately afterthe addition of the bituminous material to the aqueous medium and duringthe agitation of the mixture. Ammonium or sodium soaps of fatty acids ormixtures of fatty acids, sodium resinate, the reaction product of sodiumsilicate and oleic acid, the sodium salts of sulfonated coumarone resinand associated sulfonated coumarone-like compounds or the sodium saltsof other sulfonated benzene deriva tives may be employed as dispersingagents.

Emulsions of asphalts and readily emulsifiable 5 bituminous materialsmay be produced by adding the bituminous material in molten form to anaqueous medium while stirring. Soap-forming reagents may be mixed withthe bituminous material and aqueous medium so that upon admixture ofthese materials, the dispersing agent is formed. In such emulsificationprocedures, as well as the procedure of my copending applicationhereinabove referred to, in all cases, it has been the practice tointroduce either the total amount of emulsifier directly into theemulsion or to form the total amount of dispersing agent in situ byadding the total amount of soap-form ing constituents to the dispersedand continuous phases and causing them to react during theemulsification of the asphaltic bitumen or coal tar. coal tar with theinitial emulsion was usually subjected to treatment in a colloid mill ofany suitable type to disperse the bituminous material uniformlythroughout the aqueous medium in the form of very minute particles.

This invention is in the nature of an improvement on the emulsificationprocedures hereinabove described. I have found that if, instead ofadding the total amount of emulsifier, e. g., fatty acid soap or fattyacid soap-forming constituents, to the emulsion at the beginning orduring the emulsification procedure, as has heretofore been customary,only a portion, say from to per cent of the total emulsifier is firstintroduced and the emulsion formed and the remainder of the emulsifieris added after the emulsion thus formed is passed through a colloidmill, an emulsion of improved stability results. Emulsions made by thismethod have been found to be slower-breaking than those in which all theemulsifying agent is added at one time.

Slow-breaking emulsions are admirably suited for many uses, among whichmay be mentioned production of road aggregate involving the coating ofcrushed stone with an emulsion, followed by the coating of theemulsion-treated stone with a bituminous binder. The use of aslowbreaking emulsion for the initial treatment of porous stone resultsin increased penetration of the pores of the stone by the emulsion withconsequent improvement in the bond between the bitumen of the emulsionand the stone. If the usual relatively quick-breaking emulsion were usedto treat stone, upon contact with the stone the emulsion would break,resulting in only a surface coating of the stone with the bitumen of theemulsion and not in the penetration of the pores of the stone by thebitumen.

In practice, it has been found that an emulsion made in accordance withmy invention breaks much more slowly than an emulsion in which theconstituents thereof are in the same proportions but which was preparedby the addition of all of the emulsifying agent or constituents formingthe emulsifier during the initial stages of preparation of the emulsion.

The total quantity of emulsifying agent employed in making the emulsionof this invention may vary from 0.5 to 5 per cent by weight of theemulsion. The emulsifying agent employed should be of the type whichlowers the surface tension of the continuous phase. Sodium salts offatty acids and rosin acids are preferred. The quantity of soap added inthe second stage of the process may vary from a trace to 2.5 per cent byweight of the emulsion.

In order that my invention may be more fully understood, the followingexample of a preferred The final emulsion obtained by mixing the methodof producing an emulsion in accordance therewith is given:

An initial emulsion is produced by mixing 1.5 per cent by weight ofoleic acid, based on the weight of the completed emulsion, with 10 percent by weight of asphalt fiuX oil having a specific gravity of 1.04 anda viscosity of less than 500 seconds for c. c. at C. This mixture isheated to about 100 C. and poured into 29.3 per cent by weight of waterto which has been added 0.2 per cent by weight of caustic soda. Thematerials are vigorously agitated to produce an initial emulsion ofasphalt in sufficient water to form the final emulsion. To the initialemulsion of asphalt thus produced is added 58 per cent of liquefied coaltar having a melting point of approximately 80 F. The emulsionis'vigorously agitated during the incorporation of the coal tar, thetemperature of the emulsion thus formed falling within the range of fromto F. The emulsion thus produced is subjected to treatment in a colloidmill, such as the Charlotte mill. To this emulsion is added 1 per centof oleic acid and sufiicient caustic so that it reacts therewith to formsodium oleate. During the addition of the additional fatty acid andcaustic, the emulsion is stirred. An emulsion of improved stability willresult. By stable emulsion is meant one which does not break or invertreadily and which settles very little on standing for relatively longperiods of time, say three days or longer. For example, the stableemulsion of my invention can be passed through a colloid mill such as aCharlotte mill without breaking or inverting and will not break onstorage or while in transit for long periods of time.

The term coal tar as used in the specification and claims includes rawcoal tar, dehydrated coal tar, and stripped coal tar from which aportion of the volatile constituents have been removed. The termemulsion is used herein in a broad sense and is intended to includesuspensions or dispersions in which the disperse phase is constituted offinely divided solids as well as of liquids.

It will be understood that the invention is not limited to the specificmaterials or to the preferred form of the invention referred to hereinby way of illustration and should not be restricted to the presentdisclosure otherwise than defined by the appended claims.

I claim:

1. In a process of producing a stable emulsion the disperse phase ofwhich is constituted predominantly of tar of the group consisting ofcoal tar and water gas tar and a small amount of asphaltic bitumen, andthe continuous phase of which is constituted of an aqueous medium and anemulsifying agent, the steps comprising producing an initial emulsion ofthe asphaltic bitumen in said aqueous medium in the presence of aportion of said emulsifying agent, dispersing an amount of the tar ofthe group consisting of coal tar and water gas tar greater than theamount of the asphaltic bitumen directly in said initial emulsion andadding additional emulsifying agent directly to the emulsion thusformed, thereby obtaining a more stable emulsion than if all of theemulsifying agent were present during the said dispersing of the tar.

2. In a process of producing a stable emulsion containing as thedisperse phase a relatively large amount of tar of the group consistingof coal tar and water gas tar of a specific gravity of at least 1.15 anda smaller amount of asphalt, and the the asphalt emulsion whileagitating the emulsion, and after the addition of the tar adding to theresultant emulsion additional emulsifying agent, thereby obtaining amore stable emulsion than if all the emulsifying agent were presentduring said addition to the coal tar.

WILLIAM F. FAIR, JR.

CERTIFICATE OF CORRECTION.

atent NO. 2,087,401 July 20, 15

of the above numbered patent requiring correction as follows: Page 3,second column, line 6, claim 2, for "to" read of; and that the said Le'Henry Van Arsdale ISeal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION. atent No. 2,087,401

. Henry Van Arsdale (Seal) Acting Commissioner of Patents.

